TRENTON — Gov. Chris Christie announced today that David Samson, whose chairmanship of the Port Authority of New York and New Jersey has come under fire in recent months, has resigned.

Samson, a close ally of Christie and a former attorney general of New Jersey, is reportedly under investigation by the U.S. Attorney of New Jersey in the face of accusations that his law firm, Wolff & Samson, had enriched itself by lobbying for companies with business before the Port Authority.

He told the governor of his decision in a telephone call, Christie said.

In a statement released today, Samson said: "Over the past months, I have shared with the Governor my desire to conclude my service to the PANYNJ. The timing is now right, and I am confident that the Governor will put new leadership in place to address the many challenges ahead."

Christie said that "in line with that belief, David tendered his resignation to me this afternoon effective immediately."

The stunning announcement came at the beginning of a Statehouse news conference, the first since a a two-hour session on Jan. 9 when Christie accepted responsibility for politically charged closing of access lanes at the George Washington Bridge and announced the dismissal of two close aides.

Samson was not referred to at all in a 360-page report released Thursday that Christie had sought to look into in the wake of the bridge scandal. The report absolved Christie and any current staff members of having a role in the closing of the bridge or a subsequent coverup.

Christie also said he would "fully embrace the reforms" included in the report, which was prepared by Randy Mastro, a lawyer with the firm Gibson Dunn & Crutcher.

"I intend to work with Gov. (Andrew) Cuomo … to bring a new day to the Port Authority."